New Biomarker Found to Predict Concussion Outcomes

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Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Note that in this single-center, case-control study utilizing diffusion tensor imaging, patients with mild traumatic brain injury who had more regions of abnormally high fractional anisotropy had better quality of life and fewer post-concussion symptoms one year after injury.

CHICAGO -- A potential biomarker of the brain's neuroplasticity may predict improvements in symptoms and quality of life after a concussion, researchers said here.

In a single-center, case-control study, patients with mild traumatic brain injury (TBI) who had more abnormally high fractional anisotropy (FA) had fewer concussive symptoms and better quality of life a year after their injury than those who had less of the biomarker, according to Michael Lipton, MD, PhD, of the Albert Einstein College of Medicine in Bronx, N.Y., and colleagues.

They reported their findings during a press briefing at the Radiological Society of North America meeting here.

"If abnormally high FA represents neuroplastic effects, and if that's how people recover from brain injury, it would be possible to use this in translational studies to identify the underlying mechanisms of pathology and to identify therapies that don't look at how we fix the damage, but how we enhance the brain's ability to compensate for that damage," Lipton said during the briefing.

Concussion is a common form of brain injury, and as many as 30% of patients will have persistent functional impairment and post-concussion syndrome. But it's tough to predict which patients will have a worse recovery.

Currently, standard practice for determining recovery is looking at patient function. But Lipton said that "just because someone looks like they're back to normal doesn't mean their brain has compensated for the injury."

To better understand how the brain responds to concussion, the researchers assessed 25 patients who had been seen in the emergency department at Montefiore Medical Center in Bronx, N.Y., and compared them with 40 healthy controls.

Within 2 weeks of their injury, all patients had diffusion tensor imaging (DTI) to assess the function of the axons, bundles of nerve fiber in the brain's white matter. DTI captures the direction of movement of water molecules along those nerve bundles -- fractional anisotropy -- which in healthy white matter is highly uniform, but after injury is typically less so.

However, Lipton said, studies have also shown instances of extremely high uniform movement of water molecules after injury -- a phenomenon known as abnormally high FA -- although it hasn't been clear why this occurs.

A year after their brain injury, the study patients also completed questionnaires to assess both post-concussive symptoms (via the Rivermead PCS Questionnaire [RPQ]) and health-related quality of life (via the Sickness Impact Profile [SIP]).

Overall, all patients had detectable areas of abnormally high FA: some had more, others had less, Lipton said.

But those who had higher levels of abnormally high FA had fewer post-concussive symptoms and better health-related quality of life a year after their injury, he reported.

Higher levels significantly predicted improvements in concussive symptoms (P=0.01), as well as better outcomes in terms of the quality-of-life outcomes of mobility control (P=0.024) and psychological functioning (P=0.007).

This suggests that the "brain is compensating for its injuries," Lipton said, and that high FA "may be a manifestation of neuroplasticity." Because the brain does not form new axons, he said, it could be that the connections between existing axons are changing or strengthening.

It also implies that concussion, and perhaps traumatic brain injury in general, "is not just an event that happens. It's not like a broken bone that has to heal. The injury itself evolves over time," he said.

Although more long-term studies are needed, Lipton added that diffusion tensor imaging may eventually be useful in predicting outcomes for concussion patients, and could potentially help guide new approaches to treating such injuries.

But David Hovsepian, MD, of Stanford University Medical Center, who moderated the briefing during which the findings were presented, cautioned that the science around this potential biomarker "is just developing."

"How this description of what happens in the brain fits into clinical practice is not yet known," he said.

The researchers reported no conflicts of interest.

Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania

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